1. Field of the Invention
The present invention relates to surveyor's tools and, more particularly, to stands for a surveyor's rod.
2. Description of the Prior Art
Traditionally, a surveyor has a rod man whose function it is to hold a rod precisely vertical at a specific location upon the ground. Unless the rod is maintained precisely vertical, errors will be introduced. Relatively modern surveying equipment includes the use of a prism or reflector upon the rod to reflect an emitted beam. Again, accuracy in maintaining the rod stationary and vertical during the taking of readings is of paramount importance. Sometimes, due to fatigue or difficult terrain, a rod man may have difficulty maintaining a rod immobile and vertical for a sufficient period of time to obtain an accurate reading, which reading may require 30 seconds to 5 minutes or more. Even the most conscientious rod man will inadvertently permit minor oscillations of the rod during a reading. Moreover, during a reading, the rod man is not available to attend to other matters nor is he free to rest.
One solution used in the field to maintain the rod steady and plumbed is that of using a tripod to support the rod. This solution is very effective and the time necessary to obtain the measurements are of no moment. However, it is time consuming to set up and plumb the tripod supported rod and it cannot be easily carried from place to place. Furthermore, certain terrain may preclude the use of a tripod due to the horizontal space required and the necessity for a footing for each of the tripod points.
Various other prior art surveyor's rod tools and devices are described in the following documents. U.S. Pat. No. 2,788,578 describes a support for a surveyor's staff, which support lockingly receives the staff. Three adjustable legs extend downwardly from the support, which legs can be adjusted to maintain the staff plumb. U.S. Pat. No. 3,685,162 is directed to a support apparatus for a rod which includes means for lockingly receiving the lower tip of the rod and a pair of legs having height adjustment means to permit repositioning the rod to vertical; a bubble attached to the support provides an indication of the degree of plumbness of the rod. U.S. Pat. No. 4,527,339 is directed to an optical target having a ball and cup support arrangement. Vertical positioning and maintenance in such position may be effected by two or more legs extending downwardly and laterally of a shaft portion of the target. U.S. Pat. No. 4,490,919 describes spikes connected to bases for supporting guides usable in elevational measurements through reflected beams. U.S. Pat. No. 3,911,589 is directed to a base having an adjustable horizontal frame for supporting a vertical rod within a vertical passageway; the adjustment for verticality includes a plurality of laterally extended threadedly engaged hand wheels.